Persons familiar with the operation of tube cutting machinery have long been aware of the need for an apparatus for cutting tubular stock, such as copper pipe for cooling coils, whereby to avoid the formation of radially inwardly projecting burrs, and to reduce the amount of maintenance required to keep the cutting device in satisfactory cutting condition. It has been common practice to use cutters which are orbited about the tube in order to effect cutting thereof. This arrangement creates complicated and costly maintenance problems resulting from the complicated mechanism required to effect movement of the cutters. Moreover, this type of equipment often forms a radially inwardly projecting burr on the tube adjacent the cut. A structure of this general type is disclosed in U.S. Pat. No. 3,724,073.
To avoid the use of an orbiting cutter of the type described above, it has also been proposed to utilize a cutter which is radially actuated into engagement with the tube by means of an axially shiftable cam, as illustrated in U.S. Pat. No. 3,772,945. However, this structure employs a cam which rotates with the cutter head and has an annular groove which receives therein a cam follower which is secured to an axially shiftable activating member. This structure, due to the continued high speed rotation between the rotatable cam and the axially shiftable activating member, causes excessive wear and hence requires substantial maintenance. This structure is also more subject to binding due to the structural and functional relationships which exist between the cooperating components of the activating linkage. Further, the activating linkage results in the cutter being moved inwardly into engagement with the tube and cutting thereof at the same rate, so that the initial inward movement of the cutter prior to contact with the tube must thus be slower than desired since this speed is determined by the radial speed of the cutter during the cutting engagement thereof with the tube. The machine of this patent thus cannot be made to operate in the most efficient manner so as to result in the maximum production rate.
The known tube cutting machines, as exemplified by those described above, are also disadvantageous in that these machines generally can be made to efficiently cut only a single diameter tube, and any attempt to utilize these machines to cut a tube of a different diameter normally requires a major rebuilding of the machine, including a substantial disassembly and replacement of the cutting head structure in order to permit utilization of the machine with a different diameter tube. Needless to say, this results in not only shutdown of the machine for a long period of time, coupled with the expenditure of a large amount of manual labor, but also requires the maintaining of many different replacement parts suitable to accomodate tubes of different diameters. These known machines are thus inefficient and undesirable with respect to their capability of accomodating and cutting tubes of different diameters.
Accordingly, it is an object of the present invention to provide an improved tube cutting apparatus which overcomes the above-mentioned disadvantages. More specifically, it is an object of this invention to provide an improved tube cutting apparatus which employs a rotatable cutter head having a cutter mounted thereon and rotatable therewith, together with a cam which coacts with the cutter and also rotates with the cutting head. A phase change device is drivingly connected between the cam and the cutter and, when activated, causes a slight differential rotation between the cam and the cutter so that the latter is moved inwardly into cutting engagement with the tube. The phase change device is preferably activated by a drive arrangement which permits a rapid movement of the cutter inwardly into a position directly adjacent the tube, followed by a slower radial movement of the cutter during the cutting engagement thereof with the tube.
Another object of this invention is to provide an improved tube cutting apparatus, as aforesaid, wherein the rotatable cam employs a series of camming portions suitable for cooperation with the cutter, which camming portions are designed for use with tubes of different diameters, whereby the tooling assembly can be easily and efficiently manually adjusted with respect to the cam to permit any selected camming portion to be positioned in an activating operative relationship with the cutter. This improved cam structure thus permits the machine to be readily adjusted so as to permit efficient cutting of tubes of several different diameters without requiring a major disassembly or rebuilding of the machine, and without requiring the interchanging or replacement of machine components.
Still a further object of this invention is to provide an improved tube cutoff machine, as aforesaid, which permits a tube cutting operation to be carried out in a more efficient and time-saving manner, which results in a very desirable cutting of the tube so that the cut edges are substantially free of burrs, which can be made to operate substantially automatically, and which requires only a minimum of maintenance.
Other objects and purposes of the invention will be apparent to persons familiar with this type of machine upon reading the following specification and inspecting the accompanying drawings.